B. Husum

Distribution of SCEs in lymphocytes in persons with normal, slightly increased, and heavily increased SCEs

The distribution of SCEs in lymphocytes was examined for 165 healthy persons (58 non-smokers and 107 smokers with cigarette consumption ranging from 1 to greater than 20 per day), and for 1 patient treated with melphalan, a cytostatic drug. The data from the healthy persons did not follow a Poisson distribution. A mixed Poisson that allowed different lambda values for the 30 cells scored from each person and postulated a gamma distribution for the lambda s within the 30 cells fitted all the data examined including those from the melphalan-treated patient. In the latter case the 7 samples taken at various times after the treatment could all be represented satisfactorily with a common parameter, c, in the gamma distribution for the lambda s, even though the mean SCEs/cell varied from 9.8 to 36.8. Because the c parameter determines the spread of lambda values within the 30 cells, this suggested that the effect of the cytostatic drug was to increase all the lambda s by a constant amount. The sum of the SCEs taken over all 30 cells in a sample is a convenient summary statistic, and the transformation y = square root s + square root s + 1 behaves as a normal variate with a constant variance within a group.

Sister-chromatid exchanges in lymphocytes in women with cancer of the breast

Examination of sister-chromatid exchanges (SCE) in lymphocytes may be useful for the evaluation of exposure to mutagens/carcinogens. Information of a possible association between SCE and cancer is scarce. We therefore examined SCE in peripheral lymphocytes in 131 women, aged 17-90 years (median 51.8 years), coming to operation because of a tumor of the breast. Venous blood samples were cultivated during PHA stimulation in the presence of BrdU. After treatment with colcemid (R), fixation, treatment with bisbenzimide and staining with Giemsa, 30 metaphases were scored in each specimen. 52 patients with peroperatively demonstrated carcinoma of the breast had 9.39 +/- 0.17 SCE/cell and the remaining 79 women with non-malignant fibroadenomatosis had 9.88 +/- 0.18 SCE/cell. By multiple regression analysis it appeared that the character of the tumor, the patients age, hormone treatment and preoperative examination by mammography all were without significant influence on the SCE rate. A statistically significant correlation was found between SCE and cigarette smoking. THe 45 cigarette-smoking patients had 10.49 +/- 0.23 SCE/cell compared with 9.26 +/- 0.13 SCE/cell in the 86 non-smokers. It was concluded that spontaneous SCE in lymphocytes is not an indicator of carcinoma of the breast.

Sister Chromatid Exchanges and Structural Chromosome Aberrations in Lymphocytes in Operating Room Personnel

Information on possible chromosomal damage in humans after long‐term exposure to trace concentrations of waste anaesthetic gases is scarce. We examined peripheral lymphocytes in operating room personnel for both chromosome aberrations and sister chromatid exchanges (SCE). Following a standardized procedure of cultivation and staining, 30 cells from each person were scored for SCE and 100 cells from each person were examined for chromosome aberrations. A total of 45 persons were examined, representing anaesthetists (n= 15), operating room nurses assisting the surgeon (n=10), nurses circulating in the operating room (n = 8) and healthy, unexposed controls (n = 12). The median duration of working in the operating room was 102 months, 66 months and 66 months, respectively. Time‐weighted concentration levels of 2.5‐4.3 p.p.m. of halothane and 25–400 p.p.m. of nitrous oxide were measured in the breathing zones of the anaesthetists during mask anaesthesia. Examination of SCE and chromosome aberrations yielded corresponding qualitative results. With both tests, no statistically significant difference was observed between the four groups of persons. It was concluded that by examination of both SCE and chromosome aberrations in peripheral lymphocytes in operating room personnel, no indication was found of a mutagenic effect of long‐term exposure to trace concentrations of waste anaesthetic gases.

Normal sister-chromatid exchanges in oral contraceptive users

Sister-chromatid exchanges in peripheral lymphocytes were examined in 115 healthy women, aged 15-43 years. 63 women were on no medication at all, and 52 women used oral contraceptives. 30 metaphases from each culture were scored for SCE. In accord with previous studies, cigarette smoking increased SCE. The use of oral contraceptives had no influence on SCE on non-smoking and in cigarette-smoking women. Thus the results did not indicate any potential mutagenic effect of oral contraceptives.

Sister Chromatid Exchanges in Lymphocytes after Anaesthesia with Halothane or Enflurane

The potential mutagenicity of inhalation anaesthetics was investigated by the sister chromatid exchange (SCE) test system applied to lymphocytes in peripheral blood drawn from patients before and after anaesthesia. Twenty‐one women, aged 39–82 years (median 57.7 years) received halothane for 75–180 min (median 125 min). Fourteen other patients, aged 45–90 years (median 67.5 years) received enflurane for 90–180 min (median 130 min). In both groups the numbers of SCEs were unchanged immediately following anaesthesia and 5 days after. It was concluded that, by this method, comprising human cells exposed in vivo, there was no indication of a mutagenic effect of short‐term exposure to halothane or enflurane in anaesthetic concentrations.

Sister chromatid exchanges in peripheral lymphocytes after preoperative mammography

Examination of sister chromatid exchanges (SCE) in peripheral lymphocytes may be useful for evaluating in vivo exposure to chemical mutagens. In vitro exposure of human lymphocytes to low levels of ionizing radiation has failed to produce increased SCE rates. Scarcity of information about the SCE test system and in vivo exposure to radiation prompted the present study of SCE rates in peripheral lymphocytes in women investigated with mammography prior to operation because of a tumor of the breast. In 64 of a total of 131 women a mammography was performed before the operation. The two groups of patients were identical with respect to age, smoking habits, and incidence of malignancy of the mammary tumors. SCE rates were examined in 30 metaphases from each patient following cultivation of peripheral blood lymphocytes using the BrdU/Giemsa technique.